No. A mortgage calculator provides an estimate based on figures such as your income, deposit, spending and loan term, whereas an agreement in principle (AIP) is issued by a lender after checking information about your circumstances. Applying for an AIP may involve a soft credit search, although some lenders use a hard search, so check before applying. An AIP is not a formal mortgage offer or a guarantee that your application will be accepted. For an accurate comparison, use an FCA-authorised mortgage adviser or check the lender’s terms directly.